Kale, a leafy green, also known as a super food, comes in many varieties and will grow in many diverse locations, though some might find it tricky to overcome the plant pests that like to eat kale as much as people do.
Some of the most popular varieties are the Nero di Toscana (black kale), Winterbor (curly kale), Lacinato (dinosaur kale), Red Ursa, Russian Red, and Trochuda Beira. These are known as cole crops or fall/winter vegetables due to the way they become sweeter after being exposed to frost.
Many farmers plant this and other frost-resistant crops after the summer vegetables have been harvested, because there is still enough time to produce a full harvest before winter sets in. The cole crop plants in the Brassica uleracea family are some of the most popular vegetables in our food supply, including cabbages, broccoli, cauliflower, kohlrabi, Brussel sprouts, savoy, and collard greens.
In organic farming, these crops, though they are perennials, usually require rotating yearly because leaving the root systems in the ground can give insect populations plenty of food and a place to over-winter. Knowledgeable organic farmers remove all the debris from the grow field after harvest and use the waste to make compost for the next spring’s planting.
How to Grow Kale Organically
To begin, in an area that enjoys full sun, prepare the grow space, with lots of compost or other organic nutrient compounds like NPK 14-14-14, or 10-10-10. Soil can be amended with Sphagnum Peat Moss to ensure proper nutrient levels.
The soil should be loose and well drained as Kale likes loamy to sandy soil with a PH level of 6.0 to 6.8, and remember that your Kale will rely on calcium, potassium and boron in the soil to get the nutrients it needs to grow. Low levels of potassium in the soil will produce papery, yellow leaves.
How to Plant
Choose the variety (or varieties) you want to grow. Sow seeds ¼ to ½ inch deep and cover lightly with soil. Germination takes 5-10 days, and maturity is reached in 50-65 days. Kale can be grown in tradition garden beds, raised beds or containers, and requires about 1 inch of water per week.
For spring planting, seeds can be started indoors a few weeks before the final frost of winter or sown directly into the field when the danger of frost has passed.
For Fall harvesting, sow seeds directly or set transplants out 6-8 weeks before the first frost of winter is expected. Space your plants 12 inches apart to prevent crowding. Fertilize after 3 weeks with fish emulsion.
As leaves grow up to 12 inches in height, cut them with a knife and new growth will continue from the center. After harvest, remove all debris from the grow field and plan on rotating this crop each year. Removing root systems from the soil after harvest will prevent insect populations from over-wintering in your fertile soil.
The plant pests most responsible for damaging Cole crops are cabbage worms, loopers, moths and butterflies, aphids, caterpillars, and beetles. It is best to remove the worms and larval insects by hand, and kill them before they can multiply.
Some farmers use row covers to keep the plant pests to a minimum. Sluggo is a non-toxic OMRI Listed pesticide for slugs/worms that is safe to use in organic food production.
It is a good idea to take soil samples every other year and replenish any nutrients that are at low levels to maintain rich soil composition.
Check with your local Agricultural Extension office because many of them will ship and process your soil samples for free, and send the results to you by email. Complete instructions for gathering soil samples are available from your Agricultural Extension office and the results they send to you will include specific instructions for replacing nutrients lost from the soil, even trace elements like Boron.
And remember, the fine folks at your local Agricultural Extension Office are there to help you.